全文获取类型
收费全文 | 2600810篇 |
免费 | 178887篇 |
国内免费 | 7483篇 |
专业分类
耳鼻咽喉 | 34458篇 |
儿科学 | 85310篇 |
妇产科学 | 71639篇 |
基础医学 | 364082篇 |
口腔科学 | 69991篇 |
临床医学 | 235320篇 |
内科学 | 517191篇 |
皮肤病学 | 62518篇 |
神经病学 | 214191篇 |
特种医学 | 100041篇 |
外国民族医学 | 736篇 |
外科学 | 387038篇 |
综合类 | 50453篇 |
现状与发展 | 5篇 |
一般理论 | 969篇 |
预防医学 | 196657篇 |
眼科学 | 56850篇 |
药学 | 188605篇 |
65篇 | |
中国医学 | 5337篇 |
肿瘤学 | 145724篇 |
出版年
2021年 | 20477篇 |
2019年 | 21413篇 |
2018年 | 29422篇 |
2017年 | 22632篇 |
2016年 | 26275篇 |
2015年 | 29546篇 |
2014年 | 40557篇 |
2013年 | 60511篇 |
2012年 | 80362篇 |
2011年 | 84621篇 |
2010年 | 51053篇 |
2009年 | 49218篇 |
2008年 | 79149篇 |
2007年 | 83964篇 |
2006年 | 85659篇 |
2005年 | 81868篇 |
2004年 | 78880篇 |
2003年 | 76162篇 |
2002年 | 73428篇 |
2001年 | 128488篇 |
2000年 | 131421篇 |
1999年 | 110579篇 |
1998年 | 31290篇 |
1997年 | 27951篇 |
1996年 | 28236篇 |
1995年 | 27415篇 |
1994年 | 25087篇 |
1993年 | 23437篇 |
1992年 | 85211篇 |
1991年 | 81596篇 |
1990年 | 78839篇 |
1989年 | 76104篇 |
1988年 | 69510篇 |
1987年 | 68054篇 |
1986年 | 63581篇 |
1985年 | 60546篇 |
1984年 | 44988篇 |
1983年 | 37978篇 |
1982年 | 22475篇 |
1981年 | 20003篇 |
1979年 | 38984篇 |
1978年 | 27464篇 |
1977年 | 23274篇 |
1976年 | 21516篇 |
1975年 | 22824篇 |
1974年 | 26810篇 |
1973年 | 25383篇 |
1972年 | 23761篇 |
1971年 | 21975篇 |
1970年 | 20201篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
Samantha E. Martens Ineke H. A. P. Wolfhagen Jill R. D. Whittingham Diana H. J. M Dolmans 《Medical teacher》2020,42(5):529-535
AbstractIntroduction: Student-staff partnerships as a concept to improve medical education have received a growing amount of attention. Such partnerships are collaborations in which students and teachers seek to improve education by each adding their unique contribution to decision-making and implementation processes. Although previous research has demonstrated that students are favourable to this concept, teachers remain hesitant. The present study investigated teachers’ conceptions of student-staff partnerships and of the prerequisites that are necessary to render such partnerships successful and enhance educational quality.Method: We conducted semi-structured interviews with 14 course coordinators who lead course design teams and also teach in 4 bachelor health programmes, using Bovill and Bulley’s levels of student participation as sensitising concepts during data analysis.Results: The results pointed to three different conceptions of student-staff partnerships existing among teachers: Teachers teach and students study; teachers teach and value students’ feedback; and teachers and students co-create. The prerequisites for effective co-creation teachers identified were: Teachers must be open to involve students and create dialogues; students must be motivated and have good communication skills; the organisation must be supportive; and teachers should have the final say.Conclusion: We conclude that teachers’ conceptions are consistent with Bovill and Bulley’s levels of student participation. Under certain conditions, teachers are willing to co-create and reach the highest levels of student participation. 相似文献
52.
Benjamin Davido Rui Batista Aurélien Dinh Pierre de Truchis E.M. Terveer Bruce Roberts Ed J. Kuijper Silvia Caballero 《International journal of antimicrobial agents》2019,53(5):553-556
Background
Spontaneous decolonization of antibiotic-resistant bacteria (ARB) takes time: approximately 25% after 30 days for carbapenem-producing Enterobacteriaceae or extended-spectrum beta-lactamase-producing Enterobacteriaceae. Faecal microbiota transplantation (FMT) has been proposed as a new strategy to promote decolonization in order to reduce the risk of superinfection due to these ARB. This paper discusses the literature on the use of FMT for this indication, and the improvement levers available to promote its efficacy.Methods
Literature available to date concerning the use of FMT to eradicate ARB was reviewed, and the different factors that may have influenced the efficacy of decolonization were evaluated.Results
Four axes that could have played major roles in the efficacy of FMT were identified: bowel preparation before FMT; donor; dose; and thermal conditioning of faeces. The positive or negative impact of each on the outcome of FMT is discussed.Conclusion
Although FMT is very efficient for the eradication of Clostridium difficile, the same ‘recipe’ cannot be used for the eradication of ARB. Working together with expert centres may help to improve the efficacy of FMT for this indication, and enable the reduction of in-hospital isolation precautions. 相似文献53.
R.J. van de Peppel M.T. van der Beek L.G. Visser M.G.J. de Boer J. Wallinga 《International journal of antimicrobial agents》2019,53(3):284-293
Objectives
Triazole resistance in Aspergillus spp. is emerging and complicates prophylaxis and treatment of invasive aspergillosis (IA) worldwide. New polymerase chain reaction (PCR) tests on broncho-alveolar lavage (BAL) fluid allow for detection of triazole resistance at a genetic level, which has opened up new possibilities for targeted therapy. In the absence of clinical trials, a modelling study delivers estimates of the added value of resistance detection with PCR, and which empiric therapy would be optimal when local resistance rates are known.Design
A decision-analytic modelling study was performed based on epidemiological data of IA, extended with estimated dynamics of resistance rates and treatment effectiveness. Six clinical strategies were compared that differ in use of PCR diagnostics (used vs not used) and in empiric therapeutic choice in case of unknown triazole susceptibility: voriconazole, liposomal amphotericin B (LAmB) or both. Outcome measures were proportion of correct treatment, survival and serious adverse events.Results
Implementing aspergillus PCR tests was projected to result in residual treatment-susceptibility mismatches of <5% for a triazole resistance rate up to 20% (using voriconazole). Empiric LAmB outperformed voriconazole at resistance rates >5–20%, depending on PCR use and estimated survival benefits of voriconazole over LAmB. Combination therapy of voriconazole and LAmB performed best at all resistance rates, but the advantage over the other strategies should be weighed against the expected increased number of drug-related serious adverse events. The advantage of combination therapy over LAmB monotherapy became smaller at higher triazole resistance rates.Conclusions
Introduction of current aspergillus PCR tests on BAL fluid is an effective way to increase the proportion of patients that receive targeted therapy for IA. The results indicate that close monitoring of background resistance rates and adverse drug events are important to attain the potential benefits of LAmB. The choice of strategy ultimately depends on the probability of triazole resistance, the availability of PCR and individual patient characteristics. 相似文献54.
Nicholas Ebert Michael McGinnis William Johnson Evelyn M. Kuhn Michael E. Mitchell James S. Tweddell Ronald K. Woods 《Seminars in thoracic and cardiovascular surgery》2021,33(2):459-465
Graphical abstract summarizing the overall results of our study comparing reintervention for a main or central branch pulmonary artery reconstruction site and various patch materials. Autologous pericardium was associate with the lowest reintervention and was free. Multivariable analysis demonstrated lack of superiority of homograft branch patch, which clearly has a much higher cost. 相似文献
55.
Amanda H. Anderson Dawei Xie Xue Wang Robin L. Baudier Paula Orlandi Lawrence J. Appel Laura M. Dember Jiang He John W. Kusek James P. Lash Sankar D. Navaneethan Akinlolu Ojo Mahboob Rahman Jason Roy Julia J. Scialla James H. Sondheimer Susan P. Steigerwalt F. Perry Wilson Raymond R. Townsend 《American journal of kidney diseases》2021,77(1):56-73.e1
56.
57.
Alessandro Rambaldi Alessandra Iurlo Alessandro M. Vannucchi Bruno Martino Attilio Guarini Marco Ruggeri Nikolas von Bubnoff Marianna De Muro Mary Frances McMullin Stefania Luciani Vincenzo Martinelli Axel Nogai Vittorio Rosti Alessandra Ricco Paolo Bettica Sara Manzoni Silvia Di Tollo 《Blood cancer journal》2021,11(3)
58.
Eman Hamid MD PhD Biniyam A. Ayele MD Daniel Gams Massi MD Samia Ben Sassi MD Houyam Tibar MD Emmanuel Epenge Djonga MD Sarah Misbah El-Sadig MD Wahiba AMER EL KHEDOUD MD Julien Razafimahefa MSc Ange Eric Kouame-Assouan MD Djibrilla Ben-Adji MD Yilédoma Thierry Modeste Lengané MD Abdu Kisekka Musubire MD Muhyadin Hassan Mohamed MSc Tiwonge Elisa Phiri MBBS FCN Nsengiyumva Nestor MD Wael Abdulgader Alwahchi MSc Saara Ndinelago Neshuku MBChB FCN MMed Cassandra Ocampo MD Foksouna Sakadi MD Moulid Ali Maidal MBBS Gift Wilson Ngwende MBChB MMed FCP Juzor Hooker MB ChB MMed DCN FCP Kigocha Okeng'o MD Med MSc Augustina Charway-Felli MD PhD FGCPS Masharip Atadzhanov PhD FRCP Jonathan Carr MBChB PhD Njideka U. Okubadejo MBChB FMCP FAAN Ali Shalash MD PhD 《Movement disorders》2021,36(10):2393-2407
59.
C.A.P.F. Alves U. Lbel J.S. Martin-Saavedra S. Toescu M.H. Tsunemi S.R. Teixeira K. Mankad D. Hargrave T.S. Jacques C. da Costa Leite F.G. Gonalves A. Vossough F. D'Arco 《AJNR. American journal of neuroradiology》2021,42(5):961
BACKGROUND AND PURPOSE:Primary posterior fossa tumors comprise a large group of neoplasias with variable aggressiveness and short and long-term outcomes. This study aimed to validate the clinical usefulness of a radiologic decision flow chart based on previously published neuroradiologic knowledge for the diagnosis of posterior fossa tumors in children.MATERIALS AND METHODS:A retrospective study was conducted (from January 2013 to October 2019) at 2 pediatric referral centers, Children''s Hospital of Philadelphia, United States, and Great Ormond Street Hospital, United Kingdom. Inclusion criteria were younger than 18 years of age and histologically and molecularly confirmed posterior fossa tumors. Subjects with no available preoperative MR imaging and tumors located primarily in the brain stem were excluded. Imaging characteristics of the tumors were evaluated following a predesigned, step-by-step flow chart. Agreement between readers was tested with the Cohen κ, and each diagnosis was analyzed for accuracy.RESULTS:A total of 148 cases were included, with a median age of 3.4 years (interquartile range, 2.1–6.1 years), and a male/female ratio of 1.24. The predesigned flow chart facilitated identification of pilocytic astrocytoma, ependymoma, and medulloblastoma sonic hedgehog tumors with high sensitivity and specificity. On the basis of the results, the flow chart was adjusted so that it would also be able to better discriminate atypical teratoid/rhabdoid tumors and medulloblastoma groups 3 or 4 (sensitivity = 75%–79%; specificity = 92%–99%). Moreover, our adjusted flow chart was useful in ruling out ependymoma, pilocytic astrocytomas, and medulloblastoma sonic hedgehog tumors.CONCLUSIONS:The modified flow chart offers a structured tool to aid in the adjunct diagnosis of pediatric posterior fossa tumors. Our results also establish a useful starting point for prospective clinical studies and for the development of automated algorithms, which may provide precise and adequate diagnostic tools for these tumors in clinical practice.In the past 10 years, there has been an exponential increase in knowledge of the molecular characteristics of pediatric brain tumors, which was only partially incorporated in the 2016 World Health Organization Classification of Tumors of the Central Nervous System.1 The main update in the 2016 Classification was the introduction of the molecular profile of a tumor as an important factor for predicting different biologic behaviors of entities which, on histology, look very similar or even indistinguishable.2 A typical example is the 4 main groups of medulloblastoma: wingless (WNT), sonic hedgehog (SHH) with or without the p53 mutation, group 3, and group 4. Although they may appear similar on microscopy, these categories have distinct molecular profiles, epidemiology, prognosis, and embryologic origin.3Subsequent to the publication of the 2016 World Health Organization Classification, further studies have identified even more molecular subgroups of medulloblastoma with possible prognostic implications4 and also at least 3 new molecular subgroups of atypical teratoid/rhabdoid tumor (AT/RT)5 and several subgroups of ependymoma.6 MR imaging shows promise as a technique for differentiating histologic tumors and their molecular subgroups. This capability relies on not only various imaging characteristics but also the location and spatial extension of the tumor, evident on MR imaging, which can be traced to the embryologic origin of the neoplastic cells.5,7-10One approach to the challenge of identifying imaging characteristics of different tumors in children is to use artificial intelligence. Yet despite this exciting innovation, correctly identifying the location of the mass and its possible use as an element for differential diagnosis still requires the expertise of an experienced radiologist. Previously, D''Arco et al11 proposed a flow chart (Fig 1) for the differential diagnosis of posterior fossa tumors in children based on epidemiologic, imaging signal, and location characteristics of the neoplasm. The aims of the current study were the following: 1) to validate, in a retrospective, large cohort of posterior fossa tumors from 2 separate pediatric tertiary centers, the diagnostic accuracy of that flow chart, which visually represents the neuroadiologist''s mental process in making a diagnosis of posterior fossa tumors in children, 2) to describe particular types of posterior fossa lesions that are not correctly diagnosed by the initial flow chart, and 3) to provide an improved, clinically accessible flow chart based on the results.Open in a separate windowFIG 1.Predesigned radiologic flow chart created according to the literature before diagnostic accuracy analysis. The asterisk indicates brain stem tumors excluded from the analysis. Double asterisks indicate relative to gray matter. Modified with permission from D''Arco et al.11 相似文献